Conventionally, known artificial photosynthetic reaction center molecules are those in which an electron donor molecule and an electron acceptor molecule are linked by a covalent bond. For example, J. Phys. Chem. A 2002, 106, 3243-3252 (non-patent document 1) discloses a compound in which porphyrin and fullerene are linked by a covalent bond.
However, since it is cumbersome to synthesize a compound in which an electron donor molecule (donor) and an electron acceptor molecule (acceptor) are linked by a covalent bond, it is difficult to extend the compound to a more complex system.
On the other hand, numerous attempts have been made to form a supramolecular complex between an electron donor molecule and an electron acceptor molecule by using a non-covalent bond, so as to allow the supramolecular complex to function as an artificial photosynthetic reaction center. As compared with the use of covalent bond, the formation of a supramolecular using a non-covalent bond such as metal-ligand coordination or hydrogen bond is attracting more and more people's attention in recent years as a simple but elegant method of constructing a biological photosynthetic reaction center model system.
However, with these materials, there is the disadvantage that the charge-separated state cannot be maintained for a long period of time, so there has been a demand for a material that can be used as an artificial photosynthetic reaction center that can maintain the charge-separated state for a long period of time.
On the other hand, regarding weak π-π interaction, it has been considered that sufficient performance for a donor-acceptor-linked molecule cannot be obtained due to the weakness of its interaction. Therefore, supramolecular complexes using weak π-π interaction have not been studied.
Non-patent document 1: J. Phys. Chem. A 2002, 106, 3243-3252